Breslow et al., J.A.C.S. 99:3, 905 (1977) describe the preparation of a .DELTA..sup.9(11) compound through the 9-chlorinated derivative of a compound of the formula ##STR1##
The D-homosteroids provided by the present invention have the following general formula ##STR2## wherein the broken lines in the A- and D-rings denote optional bonds, R.sup.1 represents a hydrogen atom or a lower alkyl group and R.sup.2 represents a hydrogen or fluorine atom or a methyl group.
The term "lower alkyl" used herein means, in particular, alkyl groups which are the characterising groups of alkanols containing up to 4 carbon atoms; for example, methyl, ethyl, propyl, isopropyl, butyl and isobutyl. A preferred class of D-homosteroids of formula I comprises those in which the D-ring is saturated.
The D-homosteroids of formula I are primarily intermediates for the manufacture of pharmacologically valuable substances. However, they themselves also have pharmacological (e.g. hormonal) activity.
Examples of D-homosteroids of formula I are:
9.alpha.-Chloro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrost-4-ene-17a.beta.- carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-6.alpha.-methyl-3-oxo-D-homoandrost- 4-ene-17a.beta.-carboxylic acid, PA0 9.alpha.-chloro-6.alpha.-fluoro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrost- 4-ene-17a.beta.-carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrosta-1,4-diene-17a.b eta.-carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-6.alpha.-methyl-3-oxo-D-homoandrosta -1,4-diene-17a.beta.-carboxylic acid, PA0 9.alpha.-chloro-6.alpha.-fluoro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrosta -1,4-diene-17a.beta.-carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrosta-4,16-diene-17a. beta.-carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrosta-1,4,16-triene-1 7a.beta.-carboxylic acid, PA0 9.alpha.-chloro-6.alpha.-fluoro-17a-(m-iodobenzoyloxy)-3-oxo-D-homoandrosta -4,16-diene-17a.beta.-carboxylic acid, PA0 9.alpha.-chloro-17a-(m-iodobenzoyloxy)-6.alpha.-methyl-3-oxo-D-homoandrosta -1,4,16-triene-17a.beta.-carboxylic acid,
and the methyl, ethyl, propyl and butyl esters of these acids.
After cleaving the 9.alpha.-chlorine atom from the D-homosteroids of formula I there are obtained according to methods known per se, such as, for example, with silver perchlorate in the warm, with an alkali or alkaline earth metal carbonate in dimethylformamide or an organic base such as collidine, lutidine or pyridine or with an alkali hydroxide in an alcoholic solvent, the corresponding .DELTA..sup.9(11) -D-homosteroids. In the latter method ester groups which may be present are simultaneously also cleaved. The thus-obtained .DELTA..sup.9(11) -D-homosteroids are valuable starting materials for the manufacture of known 9.alpha.,11.beta.-dihalo-D-homosteroids or 11.beta.-hydroxy-D-homosteroids such as, for example, the D-homosteroids known from German Offenlegungsschrift No. 2,614,079.
The 9.alpha.,11.beta.-dihalo-D-homosteroids are obtained, as is well-known, by adding bromine fluoride, chlorine fluoride or chlorine to a .DELTA..sup.9(11) -D-homosteroid. The 11.beta.-hydroxy-9.alpha.-fluoro-D-homosteroids are obtained, as is well-known, by adding hypobromous acid to a corresponding .DELTA..sup.9(11) -D-homosteroid converting a resulting 11.beta.-hydroxy-9.alpha.-bromo-D-homosteroid by hydrogen bromide cleavage into a 9.beta.,11.beta.-oxido-D-homosteroid and opening the epoxide ring with hydrogen fluoride. In order to obtain a 11.beta.-hydroxy-D-homosteroid, a 11.beta.-hydroxy-9.alpha.-bromo-D-homosteroid can also be debrominated with tributyltin hydride, Raney-nickel or chromium-(II) chloride.
The D-homosteroids of formula I have the particular advantage that they offer a ready access to the 11.beta.-hydroxy-D-homosteroids which hitherto have been manufactured by microbiological hydroxylation. Whereas in microbiological methods costly provisions must be made (cultivation of the microorganisms, sterility of all fermentation media, large volumes), the 11.beta.-hydroxy-D-homosteroids can be manufactured from the D-homosteroids of formula I by steps which are technically simple to realise.
The invention is also concerned with a process for the manufacture of the D-homosteroids of formula I, which process is characterised in that a D-homosteroid of the general formula ##STR3## , wherein R.sup.1, R.sup.2 and the broken lines in the A- and D-rings have the significance given earlier,
is esterified with a m-iodobenzoylating agent, if desired a free 17a.beta.-carboxy group is esterified, and the resulting 17a.alpha.-m-iodobenzoyl ester is treated with chlorine, sulphuryl chloride or iodobenzene dichloride and irradiated with long-wave UV-light or heated in the presence of a radical-former and, if desired, a free 17a.beta.-carboxy group is esterified.
From the work of Breslow et al. [e.g. J. Amer. Chem. Soc. 96 (1974) 1973, ibid. 96 (1974) 6791] it is known that, in the case of steroids which are esterified in the 3.alpha.-position, the tertiary carbon atom in the 9-position can be chlorinated with iodobenzene dichloride under the influence of light and subsequently hydrogen chloride can be cleaved off with the formation of a 9,11-double bond. However, this procedure has the disadvantage that it can only be used on such steroids which have no carboxy group or no unprotected carbonyl group in the 17.beta.-side chain. According to the process provided by the present invention there are, however, selectively obtained 9.alpha.-chloro-3-oxo-D-homoandrost-4-ene-17a.beta.-carboxylic acids. It is also quite surprising that the chlorination takes place selectively in the 9-position, since from the work of Halpern [e.g. Chem. & Ind., 1962, 1571] it is known that steroids having double bonds react with iodobenzene dichloride to give the corresponding .alpha.-dichlorosteroids.
The process provided by the present invention is conveniently carried out by reacting a D-homosteroid starting material of formula II with a m-iodobenzoylating agent such as m-iodobenzoyl chloride or anhydride in the presence of an acid-binding agent (e.g. pyridine or triethylamine) or in the presence of a strong acid catalyst (e.g. p-toluenesulphonic acid). As the solvent for the m-iodobenzoylation there come into consideration organic solvents which do not contain hydroxyl groups (e.g. chlorinated hydrocarbons such as methylene chloride or hydrocarbons such as benzene). Thereby there is initially obtained a mixed anhydride of the steroid carboxylic acid and the m-iodobenzoic acid, which is cleaved by means of an acid (e.g. with aqueous hydrochloric acid) or by means of a base (e.g. with aqueous diethylamine) to give the desired 17a.alpha.-m-iodobenzoyloxy derivative of the D-homosteroid starting material of formula II.
The conversion of a thus-obtained 17a.alpha.-(m-iodobenzoyl)-D-homosteroid ester into a corresponding D-homosteroid of formula I is conveniently carried out in a suitable solvent. Suitable solvents are those which are not affected by the halogenating agent which is used, examples of such solvents being halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, trichloroethylene and dichloroethylene and aromatic hydrocarbons such as benzene, chlorobenzene and toluene. If desired, these solvents can also be used as mixtures with one another. Conveniently, the conversion is carried out with the exclusion of oxygen in a protective gas atmosphere. For this purpose, an inert gas such as nitrogen or argon is conducted into the solution. The irradiation with long-wave UV-light can be carried out using a commercially obtainable ultraviolet emitter (e.g. a mercury high-pressure lamp). As the radical-former there can be used an organic peroxide such as dibenzoyl peroxide, copper-(I) acetate or azodiisobutyronitrile. Conveniently, there are used 1 to 25, preferably 10, equivalents of the radical-former per 100 equivalents of the D-homosteroid to be chlorinated, in a solvent, for example one of the aforementioned halogenated hydrocarbons.
The esterification of a free 17a.beta.-carboxy group can be carried out according to methods known per se; for example, with a diazoalkane such as diazomethane in ether, or by reaction of a salt of the 17a.beta.-carboxylic acid (e.g. an alkali salt) with an alkyl halide such as methyl iodide.
The steroid starting materials of formula II, insofar as they are not known or are described hereinafter, can be prepared in analogy to known methods or methods described in the Examples.
The D-homosteroids of formula I have hormonal activity, especially on the endocrine system, and can accordingly be used as hormonally active agents (e.g. as progestational agents). They can be administered orally or parenterally at a daily dosage in the range of from about 0.005 mg/kg to 0.15 mg/kg.
The D-homosteroids of formula I can be used as medicaments; for example, in the form of pharmaceutical preparations which contain them in association with a compatible carrier material. The carrier material can be an organic or inorganic inert carrier material which is suitable for enteral, percutaneous or parenteral administration such as, for example, water, gelatin, gum arabic, lactose, starch, magnesium stearate, talc, vegetable oils, polyalkyleneglycols, petroleum jelly etc. The pharmaceutical preparations can be made up in solid form (e.g. as tablets, dragees, suppositories or capsules), in semi-solid form (e.g. as salves) or in liquid form (e.g. as solutions, suspensions or emulsions). The pharmaceutical preparations may be sterilised and/or may contain adjuvants such as preserving, stabilising, wetting or emulsifying agents, salts for varying the osmotic pressure or buffers. The pharmaceutical preparations can also contain other therapeutically valuable substances.